As a point of information, I'm using the Comply T-500 with these, not the recommended T-400. The fit is still good onto the phones, not loose at all. Handy if you've got some hanging around, as I did.
I find the music a bit more engaging over the stock large double flanges. More comfortable too!
i agree with that comment!!
i actually use the stock tips that came already installed on the re400s! they seal the best for me. they have the most neutral sound signature!